They are not the same to me, but there is a wide range of what is considered to be "pizza sauce" as well as what is considered to be "marinara sauce". My pizza sauce has no garlic, my marinara is full of it.

pizza sauce is like saying 'apple'. marinara tends to specifically be cooked, now we are in the 'red apple' category. pizza sauce has no limits or rules. marinara is usually fortified with non-traditional pizza toppings such as celery onions carrots etc to some extent, or may be simmered for an exceedingly long time.